1. Field of the Invention
The invention relates to a semiconductor housing and a method for the production of a semiconductor housing.
2. Description of the Background Art
A semiconductor housing, which is also called a chip housing, and a method for the production of the same are known from the “Fabrication and Performance of MEMS-Based Pressure Sensor Packages Using Patterned Ultra-Thick Photoresists”, Sensors 2009, 9, 6200-6218. Housings of this kind are used, among others, for accommodating sensors. To this end, the housings have an opening on their top side. The sensors on the top side of the semiconductor body, otherwise encapsulated with a casting compound, can communicate with the surroundings by means of the opening. In the case of gas sensors, for example, gas molecules can diffuse through the opening to the sensor. In the production of housings of this kind, it is important during the molding process, on the one hand, to ensure that no molding compound penetrates into the area of the opening, and, on the other, to cover particularly the bond wires and the non-sensor area, which generally comprises a circuit part, with molding compound in order to protect these areas reliably from environmental effects. In the aforementioned state of the art, a closed barrier is built on the surface of the semiconductor body for this purpose, preferably at the end of the semiconductor production process by means of a lithography process. The barrier is then pressed against the inner side of the molding tool, in which a so-called “transfer molding process” is carried out, and the molding compound is introduced into the semiconductor body up to the height of the barrier. The barrier must be made very high in order to encapsulate the bond wires and other structures on the top side with a plastic compound. Furthermore, the variation in height from barrier to barrier may only be very small in order not to damage the barrier because of the high contact pressure during pressing of the semiconductor body against the inner side of the transfer chamber.
Another option for producing openings in a semiconductor housing is disclosed in EP 0 202 701 B1. In this case, the openings are formed without the formation of barriers by means of a conventional plunger-guiding injection molding tool. The plunger in this case must be encased with a relatively cost-intensive film. Next, the plunger is lowered to the surface of the semiconductor body. The elastic film is intended to prevent, among others, damage to the semiconductor surface.
Another method for producing a semiconductor housing with an opening is disclosed in WO 2006/114005 A1. In this case, before the production of the plastic housing, a buffer structure overlapping a sensor surface is formed which is removed toward the end of the production process preferably by a wet chemical means.